Electronic control system for musical instrument



United States Patent lnventor Robert W. Tripp 14 Westview Ave. 401,Tuckahoe, New York 10707 Appl. No. 779,958 Filed Nov. 29, 1968 PatentedDec. 1, 1970 ELECTRONIC CONTROL SYSTEM FOR MUSICAL INSTRUMENT 14 Claims,3 Drawing Figs.

Primary ExaminerW. E. Ray Attorney-William E. Beatty ABSTRACT: Controlsignals representing selected chords are automatically generated as afunction of a selected root tone of the chord by the synchronizedoperation of two counters and associated logic. When a root tone(musical tone) is selected, for example, by depressing a pedal, thecounter associated with chord selection is cleared to zero at the timethe decoded count of the tone control counter represents the decodedroot tone. The two counters are thereafter counted in synchronism untila new root tone is selected by depressing another pedal and a newsynchronism is established. Each time a new root tone is selected, thecounters are synchronized with a different counting relationship so thattone selection signals can be generated to represent any selected chordtransposed to the new root note. The decoded count of the clearedcounter produces selection signals as a function of the type of chordselected, for example, by depressing a key. The selection signals inconjunction with the decoded counting signals from the control counter,enable tone selection signals to be generated by switching devicesreceiving both signals. The decoded counting signals of the tone controlcounter represent tones used in forming all chords. When there iscoincidence between the chord selection signals and the decoded tonecontrol signals, tone selection signals are generated. The signals areused with relays or equivalent switching devices to select signals fromtone generators in producing musical sounds. The system includes logicfor storing the bass and counter bass notes of a chord so that the notescan be played at a subsequent time.

CHORD swrrcHEs 1 CHORD SIGNAL GENERATOR TONE SIGNAL GE'ERAIOR TONE RELAYCCDDEF essfie l, TONE l l 8 GENERATORS g mama] um SHEET 1 OF 3 :8 LO C SE L A w NR W M m w A 8 +D m D RN R OE O 6H6 H C C 6 7 A V 4 a V J 0 n4 5J K l M osjc CLOCK STROBE SWITCHES CLEAR se LECT\ cit TONE SIGNALGENERATOR L L 9 M M R WM w W WP W cm w 0 mm T m H W m (a f E B m 7 5 5 w.4 AT A l G G S W #F m M E E WE N k m w 0 G #0 1 C\4. I cnl f 8 ATTORNEYFIG.

PATENTEU 05m 19m SHEET 2 OF SELECT CLEAR STROBE jcLocK FIG. 2

INVENTOR.

ROBERT W. TRIPP BY W ATTORNEY PATENTED UECI 197G SHEET 3 OF 3 SELECT IINVENTOR.

ROBERT w. TRIPP BY M 21 A W ATTORNEY ELECTRONIC CONTROL SYSTEM FORMUSICAL INSTRUMENT BACKGROUND OF THE INVENTION 1. Field of the InventionThis invention relates to a system for controlling the sounds generatedby a musical instrument such as an electronic organ and moreparticularly to such a system in which only the type of chord and roottone of the chord need be selected in play ing a chord and in which bassand counter bass notes of a chord are stored.

2. Description of the Prior Art Chords are usually described as acomposition of tones which blend together when sounded simultaneously.For example, a three-tone chord is described as triad, a four tone chordas a seventh. a five-tone chord as a ninth, a six-tone chord as aneleventh, etc.

Chords are based on a given tone described as the root tone. If a tonein a major or minor scale is selected as the root tone. the resultingchord usually comprises tones of that scale, The most common chords areformed from a diatonic major or minor scale.

If the root tone is the lowest tone of the selected chord, the chord isdescribed as in the fundamental position. If another tone of the chordis the lowest tone, the chord is described as inverted. In oneembodiment of the present invention, chords are inverted to maintain thetones of the selected chord within a single octave.

Electronic organs customarily provide not only the base pitchcorresponding to that of the piano, i.e., an 8-foot pitch, but alsoprovide harmonically related pitches, i.e., a 16-foot pitch which is oneoctave lower and a 4-foot pitch which is one octave higher.

In existing chord organs and ccordions, one button is provided for eachchord and each bass note. Ifsix chords are provided for each of 12tones, 72 buttons are required since one button is required for eachcombination. The proposed control system simplifies the generation ofchords by providing separate inputs for the selection of the chord typeand the root tone.

In addition, it is desirable to be able to record, or store, the bassand counter bass notes of selected chords so that the notes can besounded at a later interval. The present invention provides for storingthe notes when the chords are sounded. The counter bass tone is definedas an augmented, normal, or diminished fifth ofa chord.

The present invention not only provides for selection of chords bydepressing a key but also an additional eight chords by simplydepressing two keys. Logic interlocks are included for preventingundesired notes from sounding when more than one key is depressed andunder other conditions.

SUMMARY OF THE INVENTION Briefly, chord control logic in conjunctionwith a counter generates chord selection signals representing tones ofachord selected by depressing one or more keys.

The-root tone (musical note) of the chord is selected by depressing apedal, or key, which synchronizes the generation of the chord selectionsignals with the generation of signals representing notes, or tones,used in forming all selected chords. When the signals coincide, outputlines representing the tones ofa particular chord, are energized.

The signals are used to connect tones from the proper tone generators tothe manual or pedal section of, for example, an organ in producing thechord. Output tones from the tone generators are combined by one ofthose sections for producing the musical sound.

Logic is also included for storing states representing certain notes ofa chord, bass and counter bass notes, so that the notes can be replayedsubsequently as part ofa musical composition without the necessity for aplayer to remember the notes.

Therefore, it is an object of this invention to provide an electroniccontrol system for a musical instrument having separate chord and rootnote selection means.

It is another object of this invention to provide means for selectingchords and root notes independently without requiring separate selectionmeans for each combination of the above.

Still another object of this invention is to provide means for storingcertain notes of a selected chord for being replayed subsequently aspart ofa musical composition.

A still further object of this invention is to provide a system in whicha plurality of chord buttons can be depressed to select a chord notrepresented by a single button.

Another object of the invention is to provide interlocking logic forinhibiting certain notes from being played when certain others areselected as part ofa chord type.

These and other objects of the invention will become more apparent inconnection with the description of the preferred embodiment taken inconnection with the drawings, a brief description of which follows.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a block diagram of oneembodiment of the control system including a schematic representation ofa clock signal generator;

HQ. 2 is a schematic diagram of the root note selection portion of thesystem including coincidence detection means for generating toneselection signals; and

FIG. 3 is a schematic illustration of the chord selection portion of thesystem including logic for storing bass and counter bass notes.

DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 shows a plurality ofswitches l, operated by the foot pedals or keys of the instrument,corresponding to root tones C through 8. Outputs from the switchesprovide input signals to logic within the block identified as tonesignal generator 2, as will be shown in more detail in FIG. 2. The blockcontains a counter, decoding logic, and coincidence detection logic.

For the particular embodiment shown, it is assumed that the system isapplicable to an electronic organ. It should be noted that the system isapplicable to other musical instruments using buttons, keys or pedals ingenerating musical sounds.

When a switch is depressed, or closed, the corresponding input line tothe tone signal generator 2 is connected to an electrical ground level.It should be obvious that if two or more switches are closedsimultaneously, the note corresponding to the closed switch first in theseries controls the root tone of the chord type to be played.

The tone signal generator 2 receives a clock signal from clock generator3. The clock generator 3 also generates a strobe signal. The clocksignal provides counting pulses to the counter in the tone signalgenerator (See FIG. 2) and the strobe signal is used as an inhibitsignal as described in more detail in connection with FIG. 2.

For the embodiment shown, the clock generator 3 is comprised ofoscillator 10 which generates triggering signals to JK flip-flop 11. Atthe trailing edge of each oscillator pulse. flipflop 11 is triggered sothat its Q and output frequency is one half the frequency of theoscillator. Similarly, the Q output from flip-flop 11 provides atriggering input to flip-flop 12 so that the Q and output frequency offlip-flop 12 is one-half the frequency of flip-flop 11. The Q output offlip flop 12 is used as the clock signal for the system. The flip-flopsare used to generate a relatively square signal from the oscillatorsignal. Square signals are preferred for triggering switching devices.

The strobe signal from NAND gate 13 is low (active when the Q output offlip-flop 11 and the Q offlip-flop 12 are high.

Tone signal generator 2 generates a clear output signal on line 16 tochord signal generator 4 for setting the counter (See FIG. 3) in thechord signal generator 4 to an all zero state so that thereafter thecounter (See FIG. 3) counts in synchronism with the counter in the tonesignal generator 2. The clock signal from the clock generator 3 is usedas a count ing signal by the counter in the chord signal generator 4.

A plurality of keys, or buttons, 14, similar to the keys represented byswitches 1 into tone signal generator 2, provide chord selection inputsignals 7" through diminished to logic within the chord signal generator4. The keys are different from the FIG. 1 switches in that each key canbe inde pendently connected to ground for reasons describedsubsequently. Keys also provide bass B and counterbase CB input signalsto chord signal generator block 4 for sounding certain notes of chordspreviously played.

Output select signals from chord signal generator 4 provide inputsignals to tone signal generator 2 on line 6. The select signalsrepresenting notes C through B, are generated as a function of the roottone and chord type, bass or counterbass notes selected by a player.

For the particular embodiment shown (See FIG. 2) Flip flops arecontrolled by select signals front the chord signal generator 4 forgenerating output signals to the plurality of tone relays 8. The signalsare directed to the plurality of tone relays 8 for actuating relayscorresponding to notes (tones) of a musical scale.

The outputs from relays 8 provide inputs to select relays 9 comprisingrelay 7 for switching the 4, 8 and I6 pitch tones to the manual portionof the keyboard (not shown) and relay for switching-a pitch tone, forexample, a 16' tone, to the pedal portion of the musical system (notshown).

Relay 7 is responsive to a chord CH signal received from chord signalgenerator 4 and relay 5 is responsive to a bass B signal or a counterbass CB signal received from chord signal generator 4. Amplifiers (notshown), may be provided as required to match the control signals torelays 5,7 and 8.

The location of the octave range can be set as desired, to produce themost pleasing sound effect. The range need not be from C to B as shown.For example, it could be from F to E.

Tone generators, frequency dividers, relays, manual keyboard and pedalsection of an electronic organ are well known to persons skilled in theart. For that reason, details on those portions as well as details onplaying instructions for a particular instrument are not includedherein. Details on an electric organ to which the system describedherein is suitable can be found in a booklet entitled How Schober OrgansWork by Richard H. Dorf, copyright 1966 by The Schober OrganCorporation.

FIG. 2 shows one embodiment of the tone signal generator 2 comprisingflip-flops 20 through 31 having Q outputs representing musical tones Cthrough B, respectively. The D inputs to the flip-flops are generated bythe chord signal generator 4 as shown in FIG. 1 and as described indetail in connection with FIG. 3. The CK inputs are generated by thedecoded counts of counter 32. When the CK input to a particularflip-flop is high the Q output will be set to the same level as the Dinput. At the trailing edge of the CK input, the Q output remains inthat state until reset. The Q outputs from the flip-flops provide inputsignals to the relays designated in FIG. 1 as plurality of relays 8.

Counter 32 comprising stages A through D, is operated as a hexbinarycounter. Clock pulses from clock generator 3 drive the B stage. The Astage is driven by output pulses from the D stage. The interconnectionof the stages A through D for operating the counter in a hexbinarymanner is well known to persons skilled in the art.

Counter 32 has 12 counter states which correspond to the 12 notes, orroot tones for the embodiment system shown and described. The countingsequence is decoded as shown in the following table:

The decode logic comprises NOR gates 33 through 44 corresponding to thenotes C through B, NAND gates 45 through 51, NOR gates 54 and 55,-a'ndinverters 52 and 53.

Output signals from NOR gates 33 through 44 provide high signal levelsto the CK inputs of the flip-flops 20 through 31 as a function of theoutput states of counter 32 as indicated in the above table. Two lowinputs to a NOR gate result in a high output. Any high input to a NORgate results in a low output.

Outputs from NAND gates 45 46, 50 and 51 control the selection of groupsof three notes (C, CO, D', D0, E, F; F0, G, GO; A, A0, B) as seen by theoutput connections between the NAND gates and the NOR gates 33 through44. Each output of the NAND gates provides inputs to three NOR gates.For example, the output from NAND gate 45 provides inputs to NOR gates33, 34, and 35.

TABLE I Decoded notes The inner NAND gates 47,48, and 49 control theselection of notes within the groups of three notes. For example, NA NDgate 47 selects either the C-note in the first group, the D0 note in thesecond group, the F0 note in the third group, or the A note in thefourth group.

Outputs from NOR gates 54 and 55 with inverters 52 and 53 provide theproper logic levels to the NAND gates 45 through 51. NOR gates 54 and 55receive inputs from the B and C stages and a strobe input. The strobe isgenerated by clock generator 3 as shown in FIG. I. The strobe signal isused to inhibit the outputs from NOR gates 54 and 55 during a counttransition in counter 32.

The strobe signal may not be necessary in an ideal system. However, thetransition from one count to another in a practical system requires afinite time. During the transition period, the counter 32 output may bea state which could cause a false count to be decoded. The strobe signalis driven high during the transition period so that the outputs from theNOR gates 54 and 55 are held low until the new counter states areentered and are stable. Low outputs from the NOR gates set NAND gates47, 48, and 49 high so that all the NOR gates 33 through 44 are held lowduring the transition period. Without the strobe signal, a NOR gateoutput could be set high by a transition state and could cause a tonerelay to be erroneously actuated.

NAND gates 56 through 67 representing notes C through B receive signalsfrom the plurality of switches l as shown in FIG. 1. The NAND gates areshown with P and K inputs representing either a pedal or key input.Normally the inputs to the gates from the switches I are high. However,when a particular key or pedal is depressed its input to the connectedNAND gate is low and the output ofthe gate is set high.

NAND gates 68 through 79 receive inputs from NAND gates 56 through 67,respectively, and from NOR gates 33 through 44, respectively. When bothinputs to one of the NAND gates 68 through 79 are high, its output islow thereby indicating that the count in counter 32 is decoded as thetone selected when a player depressed a certain key. A low output signalfrom the NAND gates 68 through 79 is inverted by inverter 80 and is usedas a clear signal into the chord signal generator 4 as shown morespecifically in FIG. 3.

By way of illustration, assume a pedal (P) or key (K) input to NAND gate56, representing a C-note, is low. The output from the gate 56 is sethigh. As soon as counter 32 reaches a count of all zeros (count zeroequals note C) both inputs to NAND gate 68 are high and its output isdriven low. As a result, counter 81 (See FIG. 3) is cleared to all zerosby the clear signal from inverter 80, and counter 81 is synchronizedwith counter 32 so that when a count representing a C-note occurs incounter 32, it also occurs in counter 81.

' As another example, assume that an F-tone is selected by depressingthe pedal for providing a low input to NAND gate 61. The output from NORgate 38 is driven high when the A and B stages of counter 32 are zeroand the C and D stages are a logical one. As shown by table I, thatcounter state cor responds to a count of five and the F-note.

At the coincidence between a high output from NAND gate 61 and NOR gate38, NAND gate 73 is driven low. The inverted output from inverter 80clears counter 81 to all zeros corresponding to the F-note (count) incounter 32. In effect, the key of C of counter 81 (all zeros) istransposed to the key of F.

As a result of being able to transpose from one key note to another bysynchronizing counters 32 and 81 as described above, the necessity forproviding 12 tone selection buttons for each chord type is eliminated.The advantages of reducing the number of buttons, etc., is furtherdescn'bed and illustrated in connection with 1 16.3.

FIG. 3 shows the portion of the system used in selecting the particulartype of chord to be generated at the selected root tone. In other words,the FIG. 2 portion of the system provides for the selection of a roottone, and the FIG. 3 portion provides for selection of a chord type inthat root tone. In addi tion, the FIG. 3 system includes logic forstoring the bass and counterbass notes of the selected chords so thatthe notes can be sounded subsequently.

The chord signal generator 4 of FIG. 3 comprises the hexbi nary counter81, NOR gates 83 through 89 for decoding the counts, NAND gates 99 and100, and inverters 101 and 102 for providing the proper logic levels tothe NOR gates 83 through 89 as required for decoding certain counts. TheNAND gates 99 and 100 also receive inputs from chord CH line and thebass B and counterbass CB lines as will be described subsequently.

NAND gates 90 through 98 receive the outputs from NOR gates 83 through89 and inputs from the additional logic gates between the chord, bassand counterbass input lines .through 7, B, CB) for generating signals torepresenting musical notes of a selected chord type.

Hexbinary counter 81 receives the clear signal from inverter 80 forsetting all stages of the counter to zero. NAND gate 82, shown dotted,is included in the particular counter used in the counter embodimentshown for drive purposes. The gate 82 provides inputs to each stage ofthe counter so that each stage is simultaneously cleared. The dashedline from the gate indicates the internal connections.

The counter is identical to counter 32 described in connection with FIG.2 and the counts are decoded as shown in table 1, except that certainnotesCO, D and F are not used in the system embodiment shown anddescribed. As a result, decode logic for the excluded notes is notrequired.

If switch 19 is set to connect V to NAND gate 82, the counter is clearedas previously described. If switch 19 is in the position shown a basspedal may be operated without shifting the chord root tone. For example,after a chord button has been depressed, the counter 81 maintains itssynchronym with counter 32 even if a bass pedal is being depressed, ifthe switch 19 is in the position shown.

Outputs from NOR gates 83 through 89 provide high inputs to AND gate 90and NAND gates 91 through 98 as a function of the state of counter 81.Gates 90 through 98 are labeled by the notes corresponding to thedecoded counts of counter 81. For example, the C-note is decoded whenthe D and A counter stages are low for driving NOR gate 83 high. At thesame time, the output from NOR gate 89 is high since the C and B stagesare low. The counter therefore corresponds to a zero count (0000). Theoutput from NAND gate 103 is driven high when a chord or the bass button(not shown) is operated.

The output from AND gate 90 (C-note), when decoded as described above,provides a high input to NAND gate 104. Since the counter bass .CB lineis normally high, the output from NAND gate 104 is low for a decodedC-note. The output is inverted by NAND gate 105 to provide a high outputselection signal to the tone signal generator 2 shown in FIGS. 1 and 2.

For the example assumed, the counters 32 and 81 would previously havebeen synchronized so that the CK input to flip-flop 20 would be highduring the time the output from NAND gate is high so that the Q outputfrom the flip-flop 20 is set high for actuating a C tone relay in thetone relay block 8. p

The above example was described in terms of any chord. For theparticular embodiment being described and shown, it is possible toselect one of seven chords comprising major (M), minor (m), augmenteddiminished 6", 6", augmented, and 7". It is also possible to sound bassand counterbass notes, as previously described. Counterbass notescorrespond to the augmented, normal and diminished 5" notes of a chord.The bass notes correspond to the root note of a chord.

It should be pointed out that additional chords can be selected by thesimultaneous operation of two chord buttons (represented bychord types,M, m, etc.). For example, if the minor chord button, m, is depressedwith the 6" augmented (6+) button, a minor seventh chord (C, D0, G andA0) is selected.

For an additional example, assume that a major chord (M) in the key of Cis selected, the C-, E- and 0- notes would be required. The generationof the C-note has previously been described. The E-note selection signalis generated when the B and D stages are logical ones and the A and Cstates are logical zeros. Under those conditions, NOR gate 84 is drivenhigh, as shown in FIG. 3. However, NOR gate 84 is also used in thegeneration of the D0 note. Therefore, an additional input to NAND gate92 (E) is required to prevent both inputs from being sounded. NOR gate88 is driven high by the C and B states for the assumed example. As aresult, NAND gate 92 has two high inputs.

Since a major chord button was depressed, the M input to NAND gate wouldbe low, driving the output high. A high input to NOR gate 111 sets itsoutput low.

NOR gate 106 receives a low output from NOR gate 111. The other input toNOR gate 106 from NAND gate 113 is also low since both its inputs fromand m are high for the assumed example. Therefore, NOR gate 106 is high.The output from NAND gate 91 is inhibited by the low output from NORgate 113.

Since all inputs to NAND gate 92 are high, its output is driven low andthe output from AND gate 107 is driven low. A low output from AND gatel07'drives the output from NAND gate 105 high for generating a signalrepresenting the E-note.

A G-note, the normal 5 of the C-chord, would similarly be generatedthrough NAND gate 94 and AND gate 108.

The output from NAND gate 114 is driven low by the high output from NANDgate 110 since its other inputs from minus and plus are high. The outputfrom NAND gate 115 is driven high by the low output from 114. Theoutputs from AND gates 119 and are driven low by the low output fromNAND gate 114 for inhibiting the selection of notes F0 and G0simultaneously with the selection of the G-note. A high output from NANDgate 115 with high signals from the line, and the line provide all highinput signals to AND gate 116 for driving the output from NAND gate 94low when its other inputs are high. The output of NAND gate 117 is highwhen a chord button has been pushed. The other high inputs are derivedfrom decoded counts in counter 81 from NOR gates 85 and 88. Since theoutput of NAND gates 94 is low, the output from AND gate 108 is low andthe output from NAND gate 105 is driven high for generating the G-notesignal.

The Q output from flip-flop 27 is set high when the count in counter 32coincides with the generation of the G signal from NAND gate 105. The Qoutput is set at the trailing edge of the CK signal.

The storage feature of the system is provided by inverters 118, 134, and135, which invert the outputs from NAND gates 116, 119 and 120 and usethe inverted outputs as inputs to NAND gates 115, 133 and 126 forholding the outputs from the gates high.

For the above example, invol ving a G-note, the high output' from ANDgate 116 is inverted by inverter 118 for providing a low input to NANDgate 115. As a result, the input to NAND gate 94 from AND gate 116 isheld high until one of the other inputs to AND gate 116 is changed.

Subsequently, if it were desired to sound the counterbass note of themajor C-chord, the CB button would be depressed and the output of NANDgate 1 17 would be set high. Since the output ofNAND gate 116 wouldstill be high, a G-note (CB of major C-chord) would be sounded.

in addition, the output from NAND gate 130 would be set high foractuating a counterbass/bass relay included within selection relay block9. The chord signal from NOR gate 131 would be low since its input fromNAND gate 130 would be high. If a chord button is depressed without abass or counterbass, the CH signal is high and the chord relay of block9 is actuated.

NAND gate 126 and 133 are used in the selection of the augmented anddiminished chords. When the augmented button is depressed, the output ofNAND gate 126 is driven high and the output of AND gate 128 is drivenhigh for generating a signal from NAND gate 95 which represents a note.The note is stored by the action of inverter 135 as reviously describedfor the G-note.

A similar description also applies for generating and storing I the F0note from NAND gate 93.

As indicated by the logic interlock between AND gates 116, 119 and 120,if the augmented and diminished chord buttons are depressedsimultaneously, none of the CB-notes will sound. Only one counterbassnote can be sounded at any one time. The same inhibition applies, forexample, if the major and the diminished buttons are depressedsimultaneously. Undesired combinations of tones which would be producedby operating incorrect combinations of buttons are prevented from beingsounded.

When either the diminished or the 6 chord button is depressed, theoutput of AND gate 122 is driven low and the output of NOR gate 123 isdriven high if its other input from NAND gate 126 is also .low. if thediminished chord is selected, four notes are sounded, The A noterepresented by NAND gate 96 completes the chord.

If either the 6", 6"'+, or 7'." buttons are depressed individually, theoutput from AND gate 132 goes low and the major chord is sounded incombination with A, A0, or B depending on which of the buttons wasdepressed. However, if an additional chord button such as minor, or isdepressed, a combination of notes resulting in a new chord would besounded. For example, if the minor (m) is combined with 6+ the minor 7"chord (C, D0, G, A0) will be produced.

NOR gates 123, 124 and 125 provide an interlocking feature forpreventing adjacent of the notes (GO, A, A0 and B) from being soundedsimultaneously. The output from NAND gate 126 is used to inhibit NORgate 123. Likewise an output from NOR gate 123 will inhibit NOR gate 124and an output from NOR gate 124 will inhibit NOR gate 125.

For example, if the 6" button is depressed, the output from NOR gate 123is driven high and the output of NOR gate 124 is held low. I

[f the CB-button is depressed, the output from NAND gate 104 is drivenhigh to inhibit the generation of a bass note. The output from NOR gate131 is driven low and the output from NAND gate 99 is driven high. Thehigh output from NAND gate 99 drives the outputs from NOR gates 84 and86 low for providing an inhibiting input to NAND gates 91, 92 and 96,97, 98, respectively.'As a result, only NAND gates 93, 94, and 95 can beactuated to sound a previously stored counterbass note. Relay (FlG. 1)-is actuated by the CB output signal from NAND gate 130 so that theproper pitch of the counter bass note is provided to the pedal sectionof the musical instrument.

Subsequently, if a B button is depressed, the output from NAND gate 100is driven high for driving the outputs of NOR gates 85 and 86 low. Thelow output from NOR gates 85 and 86 provides inhibiting inputs to NANDgates 93, 94, and 96, 97, 98, respectively. in addition, NAND gate isdriven high for driving the output of NOR gate 131 low and for drivingthe output of NAND gate 99 high. As a result, the outputs of NOR gates84 and 86 are driven low for inhibiting NAND gates 91, 92, and 96, 97,98, respectively. Therefore, only AND gate 90 can be actuated forsounding a bass note. Relay 5 is actuated as indicated above by theoutput from NAN D gate 130.

if the bass or counterbass buttons are operated with any of the chordbuttons, only the bass or counterbass tones are sounded. If a chordbutton is depressed, when either the bass or counterbass button isdepressed, the output from NAND gate 130 is high and counter 81 is notinhibited, Under those circumstances, the input to NAND gate 99 from NORgate 131 would be high and relay 7 of the tone relays 9 would beactuated by the CH signal from NOR gate 131.

If either the minus or m button is depressed, the output from NAND gate113 is driven high for sounding D0 through NAND gate 91. The output fromNOR gate 106 would be driven low to inhibit the output from NAND gate92.

Although the invention has been described and illustrated in detail, itis to be understood that the same is by way of illustration and exampleonly, and is not to be taken by way of limitation. The spirit and scopeof the invention is limited only by the terms of the appended claims.

1 claim:

1. An electronic control system for a musical instrument comprising:

first means for selecting a root tone of a musical chord type;

second means for selecting a musical chord type;

first counter means for generating first cyclical signals representingtones; second counter means for generating second cyclical signalsrepresenting tones;

means responsive to said first means and said first cyclical signals forgenerating a synchronizing signal for setting said second counter meansto a predetermined count at coincidence between said cyclical signal andsaid selected root tone;

means responsive to said second means and said second cyclical signalsfor generating signals representing tones of the selected chord typehaving said root tone; and

means for detecting coincidence between said first cyclical signals andsaid chord signals for selecting musical tones of said selected chord.

2. The combination recited in claim 1, wherein said second meanscomprises means operated independently for selecting said musical chordtype and operated in combination for producing additional chords inexcess of the number of chords selected by operating said meansindependently.

3. The combination recited in claim 1 including means for storing acounter bass note of a selected musical chord type, and means foraccessing said stored note.

4. The combination recited in claim 3 including means for inhibiting thegeneration of signals representing other notes while a particularcounter bass note is being accessed.

5. The combination recited in claim 3 and further including means forgenerating a signal representing the bass root tone of a selectedmusical chord and means for inhibiting the selection of all other noteswhile said bass tone signal is being generated.

6. The combination in claim 1 including means for inhibiting thegeneration of said first cyclical signals during the transition periodbetween the counts of said first counter means.

7. The combination recited in claim 1 including means for rendering theroot tone selection means inoperable while the chord-type selectionmeans is operable.

8. A system for controlling the selection of musical notes in a musicalinstrument comprising:

root tone selection means;

tone signal generating means;

coincidence detection means for determining coincidence between a tonesignal and a selected root tone for generating a synchronizing signal;

chord-type selection means;.

first means responsive to said synchronizing signal and said chordselection means for generating signals representing tones of a selectedchord type in said selected root tone;

and

second means responsive to said generated signals and said tonegenerator means for producing musical tones corresponding to musical.notes of said selected chord type in said selected root tone.

9. The combination recited in claim 8 wherein said root tone selectionmeans includes:

counter means having 12 counts and means for decoding the counter statesand for sequentially generating signals representing each of said notes;and

said first means responsive includes second counter means for being setto a predetermined count upon receipt of each synchronizing signal.

10. The combination recited in claim 9 wherein said first meansresponsive further includes means for decoding the count of said secondcounter means and means for generating signals representing tones withinsaid selected chord type as a function of the coincidence between saiddecoded count and the chord type selected by said chord-type selectionmeans.

11. The combination recited in claim 8 including means for storing thebass and counterbass note of each selected chord type for being replayedindependently of said selected chord.

12. The combination recited in claim 11 including means for inhibitingplaying of all counterbass notes except the selected counterbass note.

13. The combination recited in claim 12 including means for inhibitingplaying of said bass note when a counterbass note is being played.

14. The combination recited in claim 8 including means for inhibitinggeneration of signals representing notes exclusive of said selectedchord 'except when two or more chords are selected simultaneously.

